He's been brought up in a very particular way, and despite being in the Army he hasn't a clue about real life.
That's true for any super rich person. They don't live the same lives as us and never will do. They all live in rich people bubbles. So what? Why is that fine for everyone else but not fine for Harry? Why on earth do you think that rich celebs who have the resources to do anything and go anywhere they like are shut-ins and prisoners in their own homes? Of course he doesn't "barely go outside" what a bizarre claim to make! They certainly have far more freedom than Will and Kate.
We have no idea who Harry's friends are, and it's weird to assume he hasn't made friends outside the UK/royal bubble. He's clearly been unhappy with royal life and press intrusion for years, if not decades, so it's reasonable so assume that he's made friendships outside of the royal bubble, and we don't know who those friends are because they're loyal and don't leak to the press.
Meghan is close to her mother and also has a solid group of close friends she's known for decades, who are likely like family to her. The children will be raised with their mum's best friends' children, as well as their own friends that they meet through school or whatever. Just like most kids. Growing up I certainly was closer to schoolmates and my mum's best friends' children than cousins, isn't that normal?
Doria is the children's only grandmother. If they'd stayed in England they likely wouldn't have seen their only grandmother that often. Pretty hypocritical that the people pearl-clutching about how terrible it is that the children won't be raised close with cousins or distant cousins are fine with the children being raised 5500 miles away from their only grandmother.
Only in Meghan threads are siblings (even half-siblings you didn't grow up with and never knew) and cousins considered more important than your children, or your own mother or grandmother. It's very weird that MN of all places is putting blood relations on such a pedestal when so many threads are about people going NC with relatives.
Anyway if William and Kate want to see their niece and nephew, or care about their kids knowing their cousins, they can very easily get on one of the private jets they regularly take to the Maldives or the Seychelles. Why is the onus on Harry and Meghan?
Harry has Invictus Games, the documentary he's making about Invictus, his Netflix deal, Sentebale and his other charity work, things like the Vax Live concert he helped organise, as well as raising two small children and no doubt spending time chilling with his wife, and seeing their own friends, and pursuing their own hobbies and interests like going to the super bowl. Both Harry and Meghan seem ambitious and driven, and hardly people to sit around a pool.